I. Chemical Treatments
Acid Pickling and Passivation: Acid pickling removes surface oxide scale and oil stains, forming a dense passivation film. This is the default process for industrial pipes, offering strong corrosion resistance.
Bright Annealing: Annealing is performed under a protective atmosphere, eliminating cold working stress and resulting in a bright and clean surface. Often used for sanitary pipes.
Phosphating and Saponification: A phosphate conversion film forms on the surface. Combined with saponification, it improves lubricity and is suitable for cold drawing, stretching, and other machining processes.
II. Mechanical Treatments
Mechanical Polishing: Grinding with abrasive belts and polishing wheels achieves mirror or brushed finishes, resulting in a high surface smoothness and easy cleaning.
Sandblasting/Shot Peening: Abrasive particles are used to blast the surface, creating a rough, matte finish. Shot peening simultaneously strengthens the surface layer and improves the pipe's fatigue resistance.
III. Electrochemical Treatments
Electrolytic Polishing: Anodic dissolution of microscopic protrusions yields an ultra-smooth surface (Ra≤0.1μm). Often used in high-cleanliness environments such as medical and pharmaceutical industries.
IV. Special/Coating Treatments
Chemical Polishing: Immersion in a specialized acid solution achieves an overall bright finish, suitable for complex-shaped pipes, and at a lower cost than electrolytic polishing.
Coating/Platement: Through methods such as plastic coating and electroplating (chromium/nickel), corrosion resistance and wear resistance are achieved, suitable for highly corrosive outdoor conditions.
Hot-Dip Galvanizing: Zinc layer thickness ≥85μm, long salt spray life, the mainstream choice for improving the outdoor weather resistance of seamless carbon steel pipes.
